Thinner ganglion cell layer thickness (GCLT) may be associated with neurological symptoms following recovery from COVID-19, according to a study published in Clinical Neurology and Neurosurgery.
Researchers collected data from 40 patients (24 women, mean age 35.9±10.8 years) who recovered from COVID-19 (mean 113±62 days following infection) and 40 age and sex matched control individuals (mean age 33.4±7.8 years, 26 women). They performed comprehensive ophthalmological examinations, optical coherence tomography (OCT), and neurological examinations on all participants. The primary outcome measure was GCLT thickness in individuals recovering from COVID-19 compared with control group participants. Researchers also sought a correlation between GCLT and COVID-19- related neurological symptoms. The team excluded individuals with previously documented retinal disease, glaucoma, and high refractive disorder.
The investigators determined that patients recovering from COVID-19 did not have significant differences in GCLT compared with the control group (P =.332). However, a subgroup analysis of patients with cognitive symptoms (brain fog) revealed a thinner GCLT for patients with cognitive symptoms compared with patients who did not experience cognitive symptoms (13±3 vs 16±4 µm; P =.002). The team also noted that participants who experienced headaches had a thinner GCLT than those who did not have headaches (14±4 vs 18±5 µm; P =.015). Investigators did not determine any significant correlations between GCLT and age, anosmia, ageusia, sleep disturbances, COVID-19 pneumonia, or smoking status.
“This study highlights an association between GCLT values measured via OCT and neurological symptoms such as cognitive disturbance (brain fog) and headache in patients who had recovered after non-severe COVID-19 infection,” according to the researchers. “Unlike other cranial nerve involvements (anosmia and ageusia), central neurological symptoms might be linked to retinal viral entry and may warrant higher surveillance.”
Study limitations include a small sample size, exclusive use of the macula for GCLT measurements, and a wide range in duration since recovery among patients.
Taskiran-Sag A, Eroglu E, Ozulken K, et al. Headache and cognitive disturbance correlate with ganglion cell layer thickness in patients who recovered from COVID-19. Clin Neurol Neurosurg. Published online April 26, 2022. doi:10.1016/j.clineuro.2022.107263